请求“num”中的成员“push_back”，它是非类类型的int ((unsigned int)((int)n))

#include <iostream>
#include <vector>
#include <numeric>
using namespace std;
std::vector<float> num;

float mean (float num[], float n)
{
    int i;
    float sum=0;
    for(i=0;i<n;i++)
    sum=sum+num[i];
    return (sum/n);

}
int main()  
{

    int minusElements;  
    int n;
    cout << "Enter number of Elements:";  
    cin >> n;



    minusElements = n - 1  ;
    int i,j;  
    float  temp;

    float f;
    for(i=0;i<n;i++)  
    {
    cin >> f;
    num.push_back(f);
    }


    cout << "Enter " << n << " numbers:\n";
    for(i=0;i<n;i++)  
    cin >> num[i];
    cin.get();
    float m = mean(&num[0], num.size());


    //if num is float[n] or float* (num of elements = n)
    float mean = std::accumulate(num, num + n, 0) / n;
    cout<<mean;
}  
//46 no match for 'operator+' in 'num + n' 
#include <iostream>
#include <vector>
#include